Symptoms and Causative Agent
Streptococcus pneumoniae bacteria, also called pneumococcal bacteria, pneumococci (plural), and pneumococcus (singular), are one of the leading causes of illness in young children. At least 90 types of pneumococcal bacteria are known to exist. As the name implies, they can cause pneumonia; however, these bacteria also can cause bloodstream infections (bacteremia), meningitis, sinusitis, and middle ear infection, among other illnesses. Collectively, the different illnesses caused by Streptococcus pneumoniae are referred to as pneumococcal disease.
Symptoms of pneumococcal disease vary based on the specific illness the bacteria have caused. Pneumococcal pneumonia symptoms include fever, chest pain, cough, and shortness of breath. When pneumococci infect normally sterile locations, so-called invasive pneumococcal disease may result. The two major types of invasive pneumococcal disease are bacteremia and meningitis (infection of the fluids and tissues surrounding the brain and/or spinal cord). Pneumococcal meningitis symptoms include fever, headache, stiffness in the neck, light sensitivity, and disorientation. Pneumococcal bacteremia may complicate localized infections such as pneumonia and is commonly associated with high fever and shaking chills.
Invasive pneumococcal disease can be fatal; survivors of meningitis may have permanent injury, including brain damage, seizures, or hearing loss.
Many people are colonized by Streptococcus pneumoniae bacteria without becoming ill. The bacteria are present in the noses or throats of many healthy individuals (5-10% of adults without children are carriers, as are 27-58% of school students) and can be spread to others via coughing or sneezing. People who are ill with pneumococcal disease can spread the bacteria in the same way as carriers can.
Individuals with sickle cell disease, certain immune deficiencies, or chronic renal disease, and those taking immunosuppressive drugs or using cochlear implants, are at an increased risk for pneumococcal infection. Cigarette smoking also increases the risk of invasive pneumococcal disease.
Treatment and Care
Antibiotics are used to treat pneumococcal disease, but some strains of the bacteria have developed resistance to some of the drugs used against them. Drug resistance can complicate treatment and increase the length of hospital stays.
Invasive pneumococcal disease and pneumococcal pneumonia can be extremely serious and often require hospitalization.
Each year in the United States, pneumococcal bacteria cause more than 4,800 cases of invasive pneumococcal disease in children younger than five years of age. Among this group, about 5% die from the infection. Of those who survive, some are left with permanent injury.
Pneumococcal bacteremia (bloodstream infection) cases total more than 50,000 each year in the United States (bacteremia occurs in approximately 25% of all pneumococcal pneumonia cases). The case fatality rate for those with pneumonia complicated by bacteremia is approximately 20%, but may be as high as 60% for elderly patients. Pneumococcal meningitis cases total about 3,000 each year in the United States, and the mortality rate is 10-30%.
Pneumococcal pneumonia causes an estimated 175,000 hospitalizations each year in the United States, and has a case fatality rate of 5-7% (in the elderly this figure is higher). Pneumococcus is the cause of up to 36% of community-acquired pneumonia cases, and 50% of community-acquired cases that require hospitalization.
Available Vaccines and Vaccination Campaigns
A pneumococcal vaccine that protected against 14 different strains was licensed in 1977, and expanded to protect against 23 strains in 1983. This vaccine is a polysaccharide vaccine called PPSV23. However, it is most effective in adults, and does not consistently generate immunity in children younger than two years old. A separate vaccine for children called PCV7 was licensed in 2000. PCV7 is a conjugate vaccine (see our article, Different Types of Vaccines, for more on how these vaccines are made); it was expanded to include protection against 13 strains in 2010, and renamed PCV13. PCV13 protects against the bacterial strains responsible for the most severe childhood pneumococcal infections.
PCV7 was added to the recommended childhood vaccination schedule in 2000 (PCV13 replaced it on the schedule in 2010). Since the initial recommendation, invasive pneumococcal disease in children has dropped by nearly 80% in the United States.
U.S. Vaccination Recommendations
Pneumococcal vaccination via PCV13 is included on the U.S. childhood immunization schedule for all children younger than five years of age. Additional protection via the polysaccharide vaccine (PPSV23) is recommended for children with certain underlying medical conditions.
The PPSV23 vaccine is also recommended for adults with certain risk factors for pneumococcal disease up to age 65, including asthma and cigarette smoking; after age 65, it is recommended for all individuals.
Vaccines and Preventable Diseases: Pneumococcal Disease - Q&A. Centers for Disease Control and Prevention, April 1, 2010. http://www.cdc.gov/vaccines/vpd-vac/pneumo/dis-faqs.htm. Accessed 7/31/2014.
Prevention of Pneumococcal Disease: Recommendations of the Advisory Committee on Immunization Practices (ACIP). (1997). Morbidity and Mortality Weekly Report, 46(RR-08); 1-24. http://www.cdc.gov/mmwr/preview/mmwrhtml/00047135.htm. Accessed 7/31/2014.
Centers for Disease Control and Prevention. Pneumococcal Disease. Epidemiology and Prevention of Vaccine-Preventable Diseases. Atkinson W, Wolfe S, Hamborsky J, McIntyre L, eds. 11th ed. Washington DC: Public Health Foundation, 2009. http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/pneumo.pdf. (579 KB). Accessed 7/31/2014.
Muller ML. Meningitis, bacterial. eMedicine Specialities. http://emedicine.medscape.com/article/961497-overview. Accessed 7/31/2014.
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Last update 31 July 2014
Timeline Entry: 1881 Pneumococcal: Bacterium Discovered
Louis Pasteur and U.S. Army physician George Miller Sternberg both independently discovered the Streptococcus pneumoniae bacterium that is responsible for cases of pneumonia and meningitis, as well as other illnesses.See This Item In The Timeline
Timeline Entry: 1977 Pneumococcal: Multi-serotype Vaccine Licensed
Robert Austrian, MD (1916-2007), Chair of Medical Research at the University of Pennsylvania, had been convinced for years that the availability of antibiotics to treat pneumococcal infections was not reason enough to abandon a pneumococcal vaccine. Austrian had published a report in 1964 documenting hundreds of fatalities from pneumococcal pneumonia over a 10-year study period despite antibiotic treatment. He was convinced that a vaccine was critical as a preventive measure against the disease.
Austrian began identifying different strains of pneumococcal bacteria, eventually finding dozens of serotypes. In 1976, he reported that a pneumococcal vaccine he had developed had proven safe and effective in clinical trials among South African gold miners. The vaccine, offering protection against 14 serotypes, was licensed by Merck in 1977.See This Item In The Timeline
Timeline Entry: 2000 Pneumococcal: Conjugate Vaccine for Children Licensed
Although Robert Austrian’s polysaccharide vaccine against pneumococcal disease was effective for adults, it did not consistently generate immunity in children less than two years old (nor in individuals with certain immunodeficiencies, such as HIV infection). In February 2000, however, a new conjugate vaccine was licensed in the United States. This vaccine, PCV7 (tradename Prevnar, manufactured by Wyeth, now Pfizer) protected against seven pneumococcal serotypes. Clinical trials showed it to be effective in children less than two years old, and it was recommended for all children aged 2-23 months in 2000. Just a few years later, in June 2004, a population-based study published in the American Journal of Public Health found that “Preliminary evidence shows that in the short study period, the use of PCV7 is correlated with decreased hospital discharge rates for invasive pneumococcal disease.” PCV7 has since been largely replaced by PCV13, licensed in 2010.See This Item In The Timeline
Timeline Entry: 2/24/2010 Pneumococcal: Vaccine for Children Expanded
Among children younger than five years old, severe pneumococcal disease had dropped by almost 80% since the introduction of the PCV7 vaccine in 2000. In 2010, PCV13 was licensed: a vaccine that protected against an additional six pneumococcal types. (There are more than 90 types of pneumococcal bacteria; PCV13 protects against the 13 that are responsible for the most severe childhood pneumococcal infections.) The Advisory Committee on Immunization Practices recommended that PCV13 replace PCV7 on the childhood immunization schedule.See This Item In The Timeline